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Home >> Mitsubishi >> 1986 >> Tredia Base >> Repair and Diagnosis >> Engine Performance >> System >> EGR System - Gasoline >> System Testing
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System Testing

  1. Check hoses for proper routing (see underhood label) and condition. Cold start engine and run at idle. Observe EGR valve for operation as speed is increased to 2500 RPM. There should be NO EGR operation after cold start. If EGR valve operates, replace thermo valve.
  2. Warm engine until coolant reaches 185-205°F (85-95°C). Increase engine speed to 2500 RPM. Observe operation of EGR valve. If EGR is inoperative, check EGR valve and thermo valve and replace as necessary.
  3. Detach Green-striped hose from thermo valve. Connect vacuum to thermo valve and attempt to create vacuum. If no vacuum can be created, valve is defective. Replace as necessary.
  4. Remove vacuum pump from thermo valve and reconnect Green-striped hose. Disconnect Green-striped hose from carburetor fitting. Connect vacuum pump to hose end.
  5. Apply 9.8 in. Hg of vacuum while opening sub EGR valve by hand. If idle speed becomes unstable, EGR valve is okay. If idle speed remains stable, EGR valve is NOT okay. Replace valve as necessary.
  6. Remove vacuum pump from hose and reconnect to carburetor. Disconnect Yellow-striped hose from EGR control valve. Connect vacuum pump to EGR control valve nipple.
  7. Apply 5.9 in. Hg of vacuum while opening sub EGR valve by hand. If idle speed becomes unstable, EGR valve is okay. If idle speed remains stable, valve is NOT okay. Replace as necessary.
  8. Remove vacuum pump from EGR control valve and reconnect Yellow-striped hose.
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